That sort of thing happens when they are left outside. Whether it was snowed/rained on, or used and not cleaned off, water likely froze in and around both the starters. I wouldn't say it was too cold to start, those little engines are designed for cold weather.
What is an inconvenience now could be very expensive if you have a big chunk of ice sitting at the bottom of the impeller's housing. Belts will burn (hopefully) or you could start breaking things.
The fix should be simply warming it up, drying it off and it should start. If you have to leave it outside, at the very least invest in a new tarp and a couple of pallets to store it. I've had to do that before.
Let us know how you make out.
Contents under pressure....
